The invention relates to a container for receiving a rheologically evolutive material for use in a consistometer and cooperating therein with measuring equipment permitting the study of the rheological evolution of this material.
The material being studied may in particular be a cement of the inorganic, organic or mixed type.
A consistometer of this kind makes it possible to follow the evolution in time of the rheological process of a progessively hardening material under conditions very close to the real conditions for which it is desired to gain knowledge of this evolution. In the construction industry, this will apply to concretes, mortars or grouts carried in rotary-container vehicles, and, in drilling, to cement grouts injected into wells.
Although the invention is not restricted to this last-mentioned application, it will be described more particularly in the case of drilling cements, because in this application experimentation conditions are particularly difficult.
In wells, particularly petroleum wells, it is necessary to pump a liquid cement in order to inject it between a metal casing and the ground formation bordering the borehole. The setting of the liquid cement isolates the various layers of the ground formation around the borehole and holds the casing in place.
For successful cementing it is important to use a liquid cement having a clearly determined pumpability time (or setting time). Too short a time would result in premature clogging, and too long a time would needlessly delay resumption of work after cementing.
A test for determining pumpability time generally takes several hours and sometimes takes up an entire working day. As it is desired to recover the cement slurry test container, an operator must be present at the end of the test in order to be able to separate the cement undergoing setting from the container holding it, before the cement hardens completely. This results in considerable problems in the organization of the work, and in sometimes the termination of a test before it has been possible to reach the maximum consistency value compatible with pumping.
It has already been proposed to make in situ measurements of rheological properties of a fluid by means of a measuring apparatus having an external cylindrical container composed of two halves capable of being joined together for use and of being separated for cleaning, the test involving rotation of shafts carrying these two halves. This system is cumbersome and would not be suitable for a consistometer in which the container receiving the material to be analysed must be placed in a chamber in which pressure and/or temperature is or are controllable. It would be even less suitable for a consistometer in which the container must itself be rotated.